Before fatty acids can enter the Krebs cycle, what process must occur?

• A. Glycolysis
• B. Lipolysis
• C. Beta-oxidation
• D. Transamination

Answer: (C)

Turning fatty acids into acetyl-CoA through beta-oxidation is what must happen before they can enter the Krebs cycle. In the mitochondria, the fatty acid is activated and then transported into the matrix, where beta-oxidation repeatedly removes two-carbon units as acetyl-CoA and generates NADH and FADH2 for energy production. Those acetyl-CoA molecules then feed into the Krebs cycle. The other processes are not the step that directly prepares fatty acids for the cycle: glycolysis handles carbohydrates, lipolysis releases fatty acids from triglycerides but doesn’t produce acetyl-CoA for the Krebs cycle, and transamination concerns amino acid metabolism.